1. Field of the Invention
The present invention relates to the field of microcontrollers. Specifically, the invention is a circuit designed to perform a power on reset (POR) function.
2. Related Art
Microcontrollers have embedded logic units, memories, power sources, and other circuits. Power On Reset (POR) circuits are typically used in microcontrollers to initialize stable power states, ensuring that booting is accomplished safely. POR circuits achieve this by forcing the microcontroller system into a reset state upon power supply activation and holding it in that state until power is stabilized, as indicated by a parameter, such as voltage, reaching a certain level. Conventionally, this is the sole function of a POR circuit.
However, several other microcontroller functions related to power state stability either go unaddressed, or require separate functionalities to enable them. In the conventional art, simply enabling more than a single POR level for a given microcontroller is one such function. Another is control of power sources supplying microcontrollers. The power for microcontrollers is typically provided by a switch mode pump (SMP), including power during boot-up. POR circuits, conventionally, are separate from SMP control, both during and after booting-up the system.
Further, certain microcontroller operational functions may be disrupted by power system instability. A microcontroller's output may be corrupted and data lost due to power instability during routine (e.g., post-startup) operation. Microcontroller output corruption is problematic, especially in critical instrumentation and control applications. In certain critical applications, variation in a microcontroller's output due to power instability can have deleterious consequences. Further still, microcontroller performance is related to power system status. Performance may be optimized by dynamically adjusting the microcontroller power system to corresponding optimal power states.
Also, microcontrollers have embedded memory subsystems, such as flash memories. Among its other functionalities, flash memory is one microcontroller system in particular, which is vulnerable to power system instability. Conventionally, these crucial operational needs are addressed by provision of system resources other than POR circuitry, if they are addressed at all.
The conventional art is problematic because it either fails to address microcontroller power stability issues beyond initial boot-up POR, requires the dedication of existing system resources to address them, or requires the provision of additional resources to address them. In the first instance, power stability problems remain unsolved. In the second two instances, the solutions are expensive.
Dedicating existing resources, internal to the microcontroller, to sense, analyze, and react to post-booting power instability removes circuitry from other possible applications. Further, these effectively internal control functions demand the expenditure of power, heat dissipation, logic, memory, and other system infrastructure and energy. These finite system resources then become unavailable for executing the design external control functions of the microcontroller. Thus, microcontroller performance can suffer.
Further, providing additional resources, e.g., adding them into the microcontroller as build-ons, to sense, analyze, and react to post-booting power instability, makes the microcontroller more expensive to manufacture and thus to acquire. Further still, such a microcontroller becomes more expensive to operate, in terms of also demanding the additional expenditures of power, heat dissipation, logic, memory, and other system infrastructure and energy to meet an effectively internal control function. These resources also thus become unavailable for executing the design external control functions of the microcontroller. Thus, the performance of microcontrollers, even with power stability resources built-on according to the conventional art, may suffer.
Conceivably, a completely new system of powering microcontrollers may be developed which regulates the stability of the power both during and after boot-up, which dispenses with the foregoing problems. However, such a system would abandon advantages inherent in existing microcontroller power systems. Also, such a system would be expensive to develop and to implement.
What is needed is a robust circuit and/or system which can effectively function to provide power on reset (POR) capabilities for a microcontroller, at more than a single level, as well as power stability functions not necessarily limited to safe boot-up. What is also needed is a circuit and/or system that can utilize POR circuitry resources to additionally control a microcontroller's switch mode pump (SMP), both during boot-up and during normal post-boot-up operations. Further, what is needed is a circuit and/or system which can apply POR circuitry resources to other power stability applications. Further still, what is needed is a circuit and/or system retaining the advantages of existing POR technology to accomplish the foregoing requirements with no extra demand on system resources or requirement for additional system resources.